Dehumidification system

ABSTRACT

A dehumidification system includes: an auxiliary heat exchanger connected to the heating medium circuit in series with the cooling heat exchanger, and provided downstream of a cooling heat exchanger in an air passage; a first air heat exchanger connected to a circulation circuit, and provided upstream of the cooling heat exchanger in the air passage; and a second air heat exchanger connected to the circulation circuit in series with the first air heat exchanger, and provided downstream of the auxiliary heat exchanger in the air passage, wherein the heating medium circuit performs a first action of sending a heating medium which is cooled in a cooling section, and sequentially flowed through the cooling heat exchanger and the auxiliary heat exchanger to the cooling section.

TECHNICAL FIELD

The present invention relates to a dehumidification system which coolsand dehumidifies air, and supplies the dehumidified air to the inside ofa room.

BACKGROUND ART

Dehumidification systems for supplying dehumidified air to the inside ofthe room have been known.

For example, Patent Document 1 discloses a dehumidification system ofthis type. The dehumidification system includes a cooling heat exchangerin an air passage in a casing. The cooling heat exchanger is connectedto a circulation circuit in which a heating medium such as water etc.circulates. The circulation circuit includes a pump for circulating theheating medium, and a cooling section for cooling the circulatingheating medium.

When the dehumidification system is operated, the pump is operated tocirculate water in the circulation circuit. The water is cooled in thecooling section, and then flows through the cooling heat exchanger. Theair flows through the air passage while a fan is operated. Thus, in thecooling heat exchanger, the water and the air exchange heat to cool theair to a dew point temperature or lower. As a result, moisture in theair is condensed to dehumidify the air. The air cooled and dehumidifiedin this manner is supplied to the inside of the room.

CITATION LIST

Patent Document

[Patent Document 1] Japanese Patent Publication No. 2006-112780

SUMMARY OF THE INVENTION Technical Problem

In the dehumidification system of this type described above, the airneeds to be cooled to the dew point temperature or lower in the coolingheat exchanger to dehumidify the air. Thus, the cooling section of thecirculation circuit needs to cool the heating medium to a relatively lowtemperature. Therefore, relatively high cooling capacity is required inthe cooling section, which reduces energy-saving effect.

In view of the foregoing, the present invention has been achieved. Theinvention is concerned with providing an energy-saving dehumidificationsystem.

Solution to the Problem

According to a first aspect of the invention, a dehumidification systemincludes: a casing (51) which forms an air passage (52) through whichair flows; a heating medium circuit (41) which includes a coolingsection (25) for cooling a predetermined heating medium, and in whichthe heating medium circulates; a cooling heat exchanger (61) which isconnected to the heating medium circuit (41), and is provided in the airpassage (52) to cool and dehumidify the air by the heating mediumflowing through the cooling heat exchanger (61) to supply thedehumidified air to the inside of a room. The dehumidification systemincludes: an auxiliary heat exchanger (62) which is connected to theheating medium circuit (41) in series with the cooling heat exchanger(61), and is arranged downstream of the cooling heat exchanger (61) inthe air passage (52); a first air heat exchanger (63) which is connectedto a circulation circuit (60, 130) in which the predetermined heatingmedium circulates, and is arranged upstream of the cooling heatexchanger (61) in the air passage (52); and a second air heat exchanger(64) which is connected to the circulation circuit (60, 130) in serieswith the first air heat exchanger (63), and is arranged downstream ofthe auxiliary heat exchanger (62) in the air passage (52), wherein theheating medium circuit (41) performs a first action of sending theheating medium which is cooled in the cooling section (25), andsequentially flowed through the cooling heat exchanger (61) and theauxiliary heat exchanger (62) to the cooling section (25).

According to the first aspect of the invention, the auxiliary heatexchanger (62) is provided downstream of the cooling heat exchanger (61)in the air passage (52) in the casing (51), the first air heat exchanger(63) is provided upstream of the cooling heat exchanger (61), and thesecond air heat exchanger (64) is provided downstream of the auxiliaryheat exchanger (62). The air flowing in the air passage (52) firstpasses through the first air heat exchanger (63). The heating mediumcirculating in the circulation circuit (60, 130) flows in the first airheat exchanger (63). Thus, the air and the heating medium exchange heat,and the air is cooled by the heating medium in the first air heatexchanger (63). On the other hand, the heating medium is heated by theair in the first air heat exchanger (63).

The air cooled in the first air heat exchanger (63) passes through thecooling heat exchanger (61). In the heating medium circuit (41)performing the first action, the heating medium cooled in the coolingsection (25) sequentially flows through the cooling heat exchanger (61)and the auxiliary heat exchanger (62). Thus, the air is cooled to a dewpoint temperature or lower by the heating medium of relatively lowtemperature, and is dehumidified in the cooling heat exchanger (61). Onthe other hand, the heating medium is heated by the air in the coolingheat exchanger (61).

The air cooled in the cooling heat exchanger (61) passes through theauxiliary heat exchanger (62). The heating medium heated in the coolingheat exchanger (61) flows in the in the auxiliary heat exchanger (62).Thus, the air is heated by the heating medium of relatively hightemperature in the auxiliary heat exchanger (62). Thus, relativehumidity of the air is reduced. On the other hand, the heating medium iscooled by the air in the auxiliary heat exchanger (62). Thus, thetemperature of the heating medium sent to the cooling section (25) ofthe heating medium circuit (41) is reduced, thereby reducing coolingcapacity required to cool the heating medium in the cooling section(25).

The air heated in the auxiliary heat exchanger (62) passes through thesecond air heat exchanger (64). The heating medium heated in the firstair heat exchanger (63) flows in the second air heat exchanger (64).Thus, the air is further heated by the heating medium of relatively hightemperature in the second air heat exchanger (64). This further reducesthe relative humidity of the air.

According to a second aspect related to the first aspect of theinvention, the dehumidification system further includes: a heatingsection (55) which is arranged downstream of the second air heatexchanger (64) in the air passage (52) to heat the air.

According to the second aspect of the invention, the heating section(55) is provided downstream of the second air heat exchanger (64). Thus,the air which passed through the second air heat exchanger (64) can beheated by the heating section (55). This can further reduce the relativehumidity of the air which passed through the heating section (55). Theair before flowing into the heating section (55) has already been heatedby the auxiliary heat exchanger (62) and the second air heat exchanger(64) as described above. Therefore, heating capacity required to heatthe air in the heating section (55) can be reduced.

According to a third aspect related to the first or second aspect of theinvention, the cooling heat exchanger (61) includes an inlet (71 a)which is positioned in a downstream part of the air passage (52), andthrough which the heating medium flows into the cooling heat exchanger(61), an outlet (71 b) which is positioned in an upstream part of theair passage (52), and through which the heating medium flows out of thecooling heat exchanger (61), and an intermediate passage (61 c) formedbetween the inlet (71 a) and the outlet (71 b).

In the cooling heat exchanger (61) according to the third aspect of theinvention, the inlet (71 a) through which the heating medium flows intothe cooling heat exchanger (61) is provided in the downstream part ofthe air passage (52), the outlet (71 b) through which the heating mediumflows out of the cooling heat exchanger (61) is provided in the upstreampart of the air passage (52), and the intermediate passage (61 c)through which the heating medium flows is formed between the inlet (71a) and the outlet (71 b). Thus, in the cooling heat exchanger (61)during the first action, the air and the heating medium flowsubstantially in opposite directions to exchange heat therebetween.Specifically, in the present invention, the cooling heat exchanger (61)during the first action can function as a so-called convection heatexchanger. With this configuration, the temperature of the air flowingout of the cooling heat exchanger (61) approaches the temperature of theheating medium flowing through the inlet (71 a). Thus, for example, ascompared with a so-called parallel heat exchanger, the cooling heatexchanger (61) can cool/dehumidify the air more effectively. On theother hand, the temperature of the heating medium flowing through theoutlet (71 b) of the cooling heat exchanger (61) approaches thetemperature of the air flowing into the cooling heat exchanger (61).Thus, for example, as compared with the parallel heat exchanger, thecooling heat exchanger (61) can increase the temperature of the heatingmedium sent from the cooling heat exchanger (61) to the auxiliary heatexchanger (62).

With this configuration, the heating medium which is cooled to arelatively low temperature in the cooling heat exchanger (61) and theair which is heated to a relatively high temperature in the cooling heatexchanger (61) exchange heat in the auxiliary heat exchanger (62). Thus,a difference in temperature between the heating medium and the air inthe auxiliary heat exchanger (62) increases, thereby effectively coolingthe heating medium by the air (i.e., effectively heating the air by theheating medium). This can further reduce the relative humidity of theair, thereby improving the dehumidification of the air. Since thetemperature of the heating medium sent to the cooling section (25) ofthe heating medium circuit (41) can further be reduced, the coolingcapacity required to cool the heating medium in the cooling section (25)can further be reduced.

According to a fourth aspect of the invention related to any one of thefirst to third aspects of the invention, the auxiliary heat exchanger(62) includes an inlet (72 a) which is positioned in the downstream partof the air passage (52), and through which the heating medium flows intothe auxiliary heat exchanger (62), an outlet (72 b) which is positionedin the upstream part of the air passage (52), and through which theheating medium flows out of the auxiliary heat exchanger (62), and anintermediate passage (62 c) formed between the inlet (72 a) and theoutlet (72 b).

In the auxiliary heat exchanger (62) according to the fourth aspect ofthe invention, the inlet (72 a) through which the heating medium flowsinto the auxiliary heat exchanger (62) is provided in the downstreampart of the air passage (52), the outlet (72 b) through which theheating medium flows out of the auxiliary heat exchanger (62) isprovided in the upstream part of the air passage (52), and theintermediate passage (62 c) through which the heating medium flows isformed between the inlet (72 a) and the outlet (72 b). Thus, in theauxiliary heat exchanger (62) during the first action, the air and theheating medium flow substantially in the opposite directions to exchangeheat therebetween. With this configuration, the temperature of the airflowing out of the auxiliary heat exchanger (62) approaches thetemperature of the heating medium flowing through the inlet (72 a).Thus, for example, as compared with the so-called parallel heatexchanger, the auxiliary heat exchanger (62) can heat the air moreeffectively. The temperature of the heating medium flowing through theoutlet (72 b) of the auxiliary heat exchanger (62) approaches thetemperature of the air flowing into the auxiliary heat exchanger (62).Thus, for example, as compared with the parallel heat exchanger, thetemperature of the heating medium sent to the cooling section (25) ofthe heating medium circuit (41) can further be reduced. This can furtherreduce the cooling capacity required to cool the heating medium in thecooling section (25).

According to a fifth aspect of the invention related to any one of thefirst to fourth aspects of the invention, the first air heat exchanger(63) includes an inlet (73 a) which is positioned in the downstream partof the air passage (52), and through which the heating medium flows intothe first air heat exchanger (63), an outlet (73 b) which is positionedin the upstream part of the air passage (52), and through which theheating medium flows out of the first air heat exchanger (63), and anintermediate passage (63 c) formed between the inlet (73 a) and theoutlet (73 b).

In the first air heat exchanger (63) according to the fifth aspect ofthe invention, the inlet (73 a) through which the heating medium flowsinto the first air heat exchanger (63) is provided in the downstreampart of the air passage (52), the outlet (73 b) through which theheating medium flows out of the first air heat exchanger (63) isprovided in the upstream part of the air passage (52), and theintermediate passage (63 c, 63 c, . . . ) through which the heatingmedium flows is formed between the inlet (73 a) and the outlet (73 b).Thus, in the first air heat exchanger (63), the air and the heatingmedium flow substantially in the opposite directions to exchange heattherebetween. In the present invention, the first air heat exchanger(63) can function as the so-called convection heat exchanger. With thisconfiguration, the temperature of the air flowing out of the first airheat exchanger (63) approaches the temperature of the heating mediumflowing through the inlet (73 a). Thus, for example, as compared withthe parallel heat exchanger, the first air heat exchanger (63) can coolthe air more effectively.

On the other hand, the temperature of the heating medium flowing throughthe outlet (73 b) of the first air heat exchanger (63) approaches thetemperature of the air flowing into the first air heat exchanger (63).Thus, for example, as compared with the parallel heat exchanger, thefirst air heat exchanger (63) can increase the temperature of theheating medium sent from the first air heat exchanger (63) to the secondair heat exchanger (64). Thus, a difference in temperature between theair and the heating medium in the second air heat exchanger (64)increases, thereby improving the heating of the air in the second airheat exchanger (64). This can further reduce the relative humidity ofthe air in the second air heat exchanger (64).

According to a sixth aspect of the invention related to any one of thefirst to fifth aspects of the invention, the second air heat exchanger(64) includes an inlet (74 a) which is positioned in the downstream partof the air passage (52), and through which the heating medium flows intothe second air heat exchanger (64), an outlet (74 b) which is positionedin the upstream part of the air passage (52), and through which theheating medium flows out of the second air heat exchanger (64), and anintermediate passage (64 c) formed between the inlet (74 a) and theoutlet (74 b).

In the second air heat exchanger (64) according to the sixth aspect ofthe invention, the inlet (74 a) through which the heating medium flowsinto the second air heat exchanger (64) is provided in the downstreampart of the air passage (52), the outlet (74 b) through which theheating medium flows out of the second air heat exchanger (64) isprovided in the upstream part of the air passage (52), and theintermediate passage (64 c) through which the heating medium flows isformed between the inlet (74 a) and the outlet (74 b). Thus, in thesecond air heat exchanger (64), the air and the heating medium can flowsubstantially in the opposite directions to exchange heat therebetween.Specifically, in the present invention, the second air heat exchanger(64) can function as the so-called convection heat exchanger.

With this configuration, the temperature of the air flowing out of thesecond air heat exchanger (64) approaches the temperature of the heatingmedium flowing through the inlet (74 a). Thus, for example, as comparedwith the parallel heat exchanger, the first air heat exchanger (63) canheat the a it more effectively. This can further reduce the relativehumidity of the air in the second air heat exchanger (64).

On the other hand, the temperature of the heating medium flowing throughthe outlet (74 b) of the second air heat exchanger (64) approaches thetemperature of the air flowing into the second air heat exchanger (64).Thus, for example, as compared with the parallel heat exchanger, thesecond air heat exchanger (64) can cool the heating medium moreeffectively. Thus, the temperature of the heating medium sent from thesecond air heat exchanger (64) to the first air heat exchanger (63) canfurther be reduced, thereby cooling the air more effectively in thefirst air heat exchanger (63).

According to a seventh aspect of the invention related to any one of thefirst to sixth aspects of the invention, the heating medium circuit (41)is configured to perform the first action, and a second action ofsending the heating medium which is cooled in the cooling section (25),and sequentially flowed through the auxiliary heat exchanger (62) andthe cooling heat exchanger (61) to the cooling section (25) in aswitchable manner.

In the heating medium circuit (41) according to the seventh aspect ofthe invention, the second action is performed in addition to theabove-described first action. In the heating medium circuit (41)performing the second action, the heating medium cooled in the coolingsection (25) sequentially flows through the auxiliary heat exchanger(62) and the cooling heat exchanger (61). Specifically, in the airpassage (52), the air sequentially flows through the cooling heatexchanger (61) and the auxiliary heat exchanger (62), while the heatingmedium flows in the opposite way. Thus, different from the first action,the heating medium cooled in the cooling section (25) first flowsthrough the auxiliary heat exchanger (62), and the air is cooled by theheating medium. As a result, the air is cooled in both of the coolingheat exchanger (61) and the auxiliary heat exchanger (62) in the secondaction, thereby improving the dehumidification of the air.

According to an eighth aspect of the invention related to any one of thefirst to seventh aspects of the invention, the dehumidification systemfurther includes: a branch passage (66) which diverts the heating mediumcirculating in the circulation circuit (60, 130), and introduces thediverted heating medium into the circulation circuit (60, 130); anauxiliary cooling section (95) which cools the heating medium flowingthrough the branch passage (66); and a diverted flow control mechanism(97) which regulates a flow rate of the heating medium flowing throughthe branch passage (66).

In the eighth aspect of the invention, the diverted flow controlmechanism (97) regulates the flow rate of the heating medium flowingthrough the branch passage (66), thereby changing the cooling capacityrequired to cool the air in the first air heat exchanger (63).Specifically, for example, when the diverted flow control mechanism (97)increases the flow rate of the heating medium flowing through the branchpassage (66), an amount of the heating medium cooled in the an auxiliarycooling unit (95) is increased. Thus, the temperature of the heatingmedium returned to the circulation circuit (60, 130) is reduced, and thecooling capacity of the first air heat exchanger (63) is reduced.

For example, when the diverted flow control mechanism (97) reduces theflow rate of the heating medium flowing through the branch passage (66),the amount of the heating medium cooled in the an auxiliary cooling unit(95) is reduced. Thus, the temperature of the heating medium returned tothe circulation circuit (60, 130) is increased, and the cooling capacityof the first air heat exchanger (63) is increased.

According to a ninth aspect of the invention related to any one of thefirst to eighth aspects of the invention, the dehumidification systemfurther includes: a flow rate control mechanism (35-37, 65) whichseparately regulates a flow rate of the heating medium flowing throughthe first air heat exchanger (63), and a flow rate of the heating mediumflowing through the second air heat exchanger (64).

In the ninth aspect of the invention, the flow rate control mechanism(35-37, 65) can separately regulate the flow rates of the heating mediumflowing through the first air heat exchanger (63) and the second airheat exchanger (64). Thus, for example, cooling/dehumidifying capacityrequired to cool/dehumidify the air in the first air heat exchanger (63)can be changed by changing the flow rate of the heating medium flowingthrough the first air heat exchanger (63). Further, air heating capacityrequired to heat the air in the second air heat exchanger (64) can bechanged by changing the flow rate of the heating medium flowing throughthe second air heat exchanger (64).

According to a tenth aspect of the invention related to any one of thefirst to ninth aspects of the invention, the dehumidification systemfurther includes: an exhaust passage (59) through which the air in theroom is discharged outside; and a sensible heat exchanger (68) in whichthe heating medium flowing through the circulation circuit (60, 130) andthe air flowing through the exhaust passage (59) exchange heat.

In the tenth aspect of the invention, the room air is discharged outsidethrough the exhaust passage (59). In this case, the heating medium usedto cool the air in the first air heat exchanger (63) exchanges heat withthe room air in the sensible heat exchanger (68) provided in the exhaustpassage (59). Thus, for example, when the temperature of the room airflowing through the exhaust passage (59) is relatively low, cold of theroom air can be added to the heating medium. This can improve thecooling of the air in the first air heat exchanger (63).

For example, when the temperature of the room air flowing through theexhaust passage (59) is relatively high, the heat of the room air can beadded to the heating medium. This can improve the heating of the air inthe second air heat exchanger (64).

According to an eleventh aspect of the invention related to any one ofthe first to tenth aspects of the invention, the dehumidification systemfurther includes: a bypass passage (140) which transfers the air in theair passage (52) upstream of the first air heat exchanger (63) to thedownstream of the cooling heat exchanger (61); and a bypass flow controlmechanism (141) which regulates a flow rate of the air flowing throughthe bypass passage (140).

In the eleventh aspect of the invention, the bypass passage (140) isprovided in the air passage (52), and the flow rate of the air flowingthrough the bypass passage (140) can be regulated by the bypass flowcontrol mechanism (141). For example, when the flow rate of the airflowing through the bypass passage (140) is increased, the flow rate ofthe air which is cooled/dehumidified in the first air heat exchanger(63) and the cooling heat exchanger (61) is reduced. Thus, an amount oflatent heat handled by the dehumidification system is reduced. Forexample, when the flow rate of the air flowing through the bypasspassage (140) is reduced, the flow rate of the air which iscooled/dehumidified in the first air heat exchanger (63) and the coolingheat exchanger (61) is increased. Thus, in the present invention,changing the flow rate of the air flowing through the bypass passage(140) allows operation corresponding to a latent heat load.

ADVANTAGES OF THE INVENTION

In the present invention, the air is cooled in advance by the heatingmedium flowing through the first air heat exchanger (63), and then theair is cooled/dehumidified in the cooling heat exchanger (61). This canreduce the cooling capacity required to cool the air in the cooling heatexchanger (61), and can reduce the cooling capacity required to cool theair in the cooling section (25) of the heating medium circuit (41). Inthe auxiliary heat exchanger (62), the air is heated by heat collectedfrom the air in the cooling heat exchanger (61). This can improve thedehumidifying capacity, and the temperature of the heating medium sentto the cooling section (25) can be reduced. Thus, the cooling capacityrequired in the cooling section (25), and an amount of the heatingmedium circulating in the heating medium circuit (41) can be bothreduced. In the second air heat exchanger (64), the air is heated byheat collected from the air in the first air heat exchanger (63). Thiscan further improve the dehumidifying capacity, and cold collected fromthe air can be used again to cool the air in the first air heatexchanger (63). Thus, the present invention can improve thedehumidifying capacity, while significantly reducing energy consumptionof the dehumidification system.

In the second aspect of the invention, the air can be heated in theauxiliary heat exchanger (62) and the second air heat exchanger (64),thereby reducing the heating capacity required to heat the air in theheating section (55). This can further reduce the energy consumption ofthe dehumidification system.

In the third aspect of the invention, the air and the heating mediumflow in the opposite directions in the cooling heat exchanger (61) toexchange heat therebetween. Thus, in the cooling heat exchanger (61)during the first action, the air can be cooled to a lower temperature,and the heating medium can be heated to a higher temperature. This canreduce the cooling capacity required in the cooling section (25), andthe heating capacity required in the heating section (55) etc., therebyfurther reducing energy consumption of the dehumidification system. Inthe fourth aspect of the invention, the heating medium and the air flowin the opposite directions in the auxiliary heat exchanger (62) duringthe first action to exchange heat therebetween. Thus, the temperature ofthe heating medium flowing out of the auxiliary heat exchanger (62) isfurther reduced, and the temperature of the air passing through theauxiliary heat exchanger (62) is further increased. This can furtherreduce the cooling capacity required in the cooling section (25), andthe heating capacity required in the heating section (55) etc.

In the fifth aspect of the invention, the air and the heating mediumflow in the opposite directions in the first air heat exchanger (63) toexchange heat therebetween. Thus, the air can be cooled to a lowertemperature, and the heating medium can be heated to a highertemperature in the first air heat exchanger (63). This can furtherreduce the cooling capacity required in the cooling heat exchanger (61),and the heating capacity required in the heating section (55), and canfurther reduce the energy consumption of the dehumidification system.

In the sixth aspect of the invention, the air and the heating mediumflow in the opposite directions in the second air heat exchanger (64) toexchange heat therebetween.

Thus, the air can be heated more effectively in the second air heatexchanger (64), and an amount of the cold collected from the air in thesecond air heat exchanger (64) is increased. Therefore, the air iscooled more effectively in the first air heat exchanger (63).

In the seventh aspect of the invention, the second action of feeding theair to sequentially flow through the cooling heat exchanger (61) and theauxiliary heat exchanger (62), and simultaneously feeding the heatingmedium to sequentially flow through the auxiliary heat exchanger (62)and the cooling heat exchanger (61) is performed. Thus, different fromthe first action, the air can be cooled in both of the cooling heatexchanger (61) and the auxiliary heat exchanger (62). Therefore, the aircan be dehumidified more effectively in the second action than in thefirst action. Even when the temperature and humidity of the target airare high, the air can reliably be dehumidified by performing the secondaction.

In the eighth aspect of the invention, the flow rate of the heatingmedium sent to the branch passage (66) is regulated to suitably regulatethe cooling capacity required in the first air heat exchanger (63).Thus, the dehumidification system can be operated in accordance with thehumidity and temperature of the target air. Since the auxiliary coolingunit (95) reduces the temperature of the heating medium, the air can becooled/dehumidified also in the second air heat exchanger (64).

In the ninth aspect of the invention, the flow rate of the heatingmedium flowing through the first air heat exchanger (63), and the flowrate of the heating medium flowing through the second air heat exchanger(64) can separately be regulated. Thus, the cooling capacity required tocool the air in the first air heat exchanger (63), and the heatingcapacity required to heat the air in the second air heat exchanger (64)can separately be changed. Therefore, the operation can be optimized inaccordance with operating conditions.

In the tenth aspect of the invention, the air discharged from the insideof the room and the heating medium flowing through the heating mediumcircuit (41) exchange heat in the sensible heat exchanger (68). When theroom is cooled, the cold of the air is added to the heating mediumflowing through the heating medium circuit (41), thereby cooling the airmore effectively in the first air heat exchanger (63). For example, whenthe room is heated, the heat of the air is added to the heating mediumflowing through the heating medium circuit (41), thereby heating the airmore effectively in the second air heat exchanger (64).

In the eleventh aspect of the invention, the flow rate of the airflowing through the bypass passage (140) is regulated to regulate theflow rate of the air flowing through the first air heat exchanger (63)and the cooling heat exchanger (61). Thus, the dehumidifying capacityrequired to dehumidify the air, and the cooling capacity required tocool the air in the dehumidification system can separately be regulated.This allows cooling/dehumidifying operation optimized in accordance withthe operating conditions and needs associated with the operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a general structure of adehumidification system according to a first embodiment.

FIG. 2 is a schematic view illustrating heat exchangers in an airconditioning unit.

FIG. 3 is a schematic view illustrating the heat exchangers in the airconditioning unit together with a flow of a heating medium during heatrecovery operation.

FIG. 4 is a schematic view illustrating the heat exchangers in the airconditioning unit together with a flow of the heating medium duringdehumidification-dominant operation.

FIG. 5 is a schematic view illustrating a general structure of adehumidification system according to a first alternative.

FIG. 6 is a schematic view illustrating heat exchangers in an airconditioning unit according to the first alternative together with aflow of a heating medium when a three-way valve is set to a first state.

FIG. 7 is a schematic view illustrating the heat exchangers in the airconditioning unit according to the first alternative together with aflow of the heating medium when the three-way valve is set to a secondstate.

FIG. 8 is a schematic view illustrating a general structure of adehumidification system according to a second alternative.

FIG. 9 is a schematic view illustrating a general structure of adehumidification system according to a third alternative.

FIG. 10 is a schematic view illustrating a general structure of adehumidification system according to a fourth alternative.

FIG. 11 is a schematic view illustrating a general structure of adehumidification system according to a fifth alternative.

FIG. 12 is a schematic view illustrating a general structure of adehumidification system according to a sixth alternative.

FIG. 13 is a schematic view illustrating a general structure of adehumidification system according to a seventh alternative.

FIG. 14 is a schematic view illustrating a general structure of an airconditioning unit of another dehumidification system according to theseventh alternative.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail belowwith reference to the drawings.

[First Embodiment]

A dehumidification system according to a first embodiment regulates roomhumidity and room temperature, and constitutes, for example, an airconditioning system (10) applied to semiconductor factories etc. Asshown in FIG. 1, the air conditioning system (10) according to the firstembodiment is configured to take outside air (OA), conditions humidityand temperature of the air, and supplies the conditioned air as supplyair (SA) to the inside of a room. The air conditioning system (10)includes a chiller unit (20), and an air conditioning unit (50). The airconditioning system (10) further includes a refrigerant circuit (21), aradiation circuit (31), and a heating medium circuit (41).

<Structure of Refrigerant Circuit>

The refrigerant circuit (21) is included in the chiller unit (20). Therefrigerant circuit (21) constitutes a closed circuit filled with arefrigerant. A compressor (22), a radiator (23), an expansion valve(24), and an evaporator (25) are connected to the refrigerant circuit(21). The refrigerant circuit (21) performs a vapor compressionrefrigeration cycle by circulating the refrigerant.

The radiator (23) includes a first heat transfer pipe (23 a) connectedto the refrigerant circuit (21), and a second heat transfer pipe (23 b)connected to the radiation circuit (31). Thus, the refrigerant circuit(21) is connected to the radiation circuit (31) through the radiator(23). In the radiator (23), the refrigerant flowing through the firstheat transfer pipe (23 a) and a heating medium flowing through thesecond heat transfer pipe (23 b) exchange heat. The evaporator (25)includes a first heat transfer pipe (25 a) connected to the refrigerantcircuit (21), and a second heat transfer pipe (25 b) connected to theheating medium circuit (41). Thus, the refrigerant circuit (21) isconnected to the heating medium circuit (41) through the evaporator(25). In the evaporator (25), the refrigerant flowing through the firstheat transfer pipe (25 a) and the heating medium flowing through thesecond heat transfer pipe (25 b) exchange heat.

<Structure of Radiation Circuit>

The radiation circuit (31) constitutes a closed circuit filled withwater as the heating medium. The radiator (23), a water pump (32), and acooling tower (33) are connected to the radiation circuit (31). Thewater pump (32) transfers and circulates the water in the radiationcircuit (31). The cooling tower (33) constitutes a cooling member forcooling the water circulating in the radiation circuit (31). An arrowshown near the water pump (32) in the drawings indicates a direction ofthe water circulated in the radiation circuit (31).

<Structure of Circulation Circuit>

The heating medium circuit (41) constitutes a closed circuit filled withwater as the heating medium. The evaporator (25), a chiller pump (42),and a cooling heat exchanger (61) are connected to the heating mediumcircuit (41). The evaporator (25) constitutes a heating medium coolingsection for cooling the heating medium circulating in the heating mediumcircuit (41). The chiller pump (42) constitutes a heating mediumtransfer mechanism for transferring and circulating the water in theheating medium circuit (41). Details of the cooling heat exchanger (61)will be described later. An arrow shown near the chiller pump (42) inthe drawings indicates a direction of the water flowing in the heatingmedium circuit (41).

A water bypass pipe (43) is connected to the heating medium circuit(41). An end of the water bypass pipe (43) is connected between thechiller pump (42) and the cooling heat exchanger (61). The other end ofthe water bypass pipe (43) is connected between the cooling heatexchanger (61) and the evaporator (25). A motor-operated bypass valve(44) is provided in the water bypass pipe (43). The motor-operatedbypass valve (44) constitutes a flow rate control valve which canregulate the degree of opening of the water bypass pipe (43). In FIG. 1(and FIGS. 5, and 8-14), pipes are partially omitted to schematicallyshow how the pipes are communicated with each other during a firstaction described in detail later.

<Structure of Air Conditioning Unit>

The air conditioning unit (50) includes a casing (51) which is in theshape of a horizontally oriented flat rectangular parallelepiped. An airpassage (52) through which air flows is formed in the casing (51). Aninlet end of the air passage (52) is connected to an end of an inletduct (53). The other end of the inlet duct (53) is opened outside theroom. An outlet end of the air passage (52) is connected to an end of asupply duct (54). The other end of the supply duct (54) is opened in aroom (5).

The air passage (52) includes a first air heat exchanger (63), thecooling heat exchanger (61), an auxiliary heat exchanger (62), a secondair heat exchanger (64), an electric heater (55), a sprinkler (56), anda blower (57) sequentially arranged from upstream to downstream in theair passage. The electric heater (55) is provided downstream of thesecond air heat exchanger (64) to constitute an air heating section forheating the air. The sprinkler (56) constitutes a humidifying sectionwhich sprinkles water in a tank (not shown) in the air through a nozzle.The blower (57) constitutes an air transfer mechanism which transfersthe air in the air passage (52).

The cooling heat exchanger (61) described above constitutes an aircooling section for cooling the air to a dew point temperature or lower.As shown in FIGS. 2-4, the cooling heat exchanger (61) includes aplurality of fins (61 a), and a heat transfer tube (61 b) penetratingthe fins (61 a) to constitute a so-called fin-and-tube heat exchanger.The cooling heat exchanger (61) includes fin sets each containing fivefins arranged in a direction of air flow.

The cooling heat exchanger (61) includes an inlet (71 a) which ispositioned in a downstream part of the air passage (52), and throughwhich water flows into the cooling heat exchanger (61), and an outlet(71 b) which is positioned in an upstream part of the air passage (52),and through which water flows out of the cooling heat exchanger (61). Afirst inlet pipe (71) and a first outlet pipe (72) are connected to theinlet (71 a) and the outlet (71 b) of the cooling heat exchanger (61),respectively.

Each of the inlet (71 a) and the outlet (71 b) of the cooling heatexchanger (61) is divided into two or more branches by a flow divider.The branches of the inlet (71 a) are connected to inlet ends of aplurality of paths (61 c, 61 c, . . . ) in the cooling heat exchanger(61), and the branches of the outlet (71 b) are connected to outlet endsof a plurality of paths (61 c, 61 c, . . . ) in the cooling heatexchanger (61). The paths (61 c, 61 c, . . . ) are aligned in thevertical direction to be parallel with each other, and extend betweenthe inlet (71 a) and the outlet (71 b). The paths (61 c, 61 c, . . . )constitute an intermediate passage formed between the inlet (71 a) andthe outlet (71 b).

The auxiliary heat exchanger (62) is provided downstream of the coolingheat exchanger (61). The auxiliary heat exchanger (62) includes aplurality of fins (62 a), and a heat transfer tube (62 b) penetratingthe fins (62 a) to constitute the so-called fin-and-tube heat exchanger.The auxiliary heat exchanger (62) includes fin sets each containingthree fins arranged in the direction of air flow. Specifically, thenumber of the fins in each fin set of the auxiliary heat exchanger (62)is smaller than the number of the fins in each fin set of the coolingheat exchanger (61).

The auxiliary heat exchanger (62) includes an inlet (72 a) which ispositioned in the downstream part of the air passage (52), and throughwhich water flows into the auxiliary heat exchanger (62), and an outlet(72 b) which is positioned in the upstream part of the air passage (52),and through which water flows out of the auxiliary heat exchanger (62).A second inlet pipe (73) and a second outlet pipe (74) are connected tothe inlet (72 a) and the outlet (72 b) of the auxiliary heat exchanger(62), respectively.

Like in the cooling heat exchanger (61) described above, the inlet (72a) and the outlet (72 b) of the auxiliary heat exchanger (62) arebranched, and a plurality of paths (62 c, 62 c, . . . ) are formed as anintermediate passage between the inlet (72 a) and the outlet (72 b).

The cooling heat exchanger (61) and the auxiliary heat exchanger (62)are coupled through a first coupling pipe (75) and a second couplingpipe (76). The inlet (71 a) of the cooling heat exchanger (61) and theoutlet (72 b) of the auxiliary heat exchanger (62) communicate with eachother through the first coupling pipe (75). The outlet (71 b) of thecooling heat exchanger (61) and the inlet (72 a) of the auxiliary heatexchanger (62) communicate with each other through the second couplingpipe (76).

The first inlet pipe (71) has a first valve (81), the first outlet pipe(72) has a second valve (82), the second inlet pipe (73) has a thirdvalve (83), the second outlet pipe (74) has a fourth valve (84), thefirst coupling pipe (75) has a fifth valve (85), and the second couplingpipe (76) has a sixth valve (86). The valves (81-86) are configured toopen or close the corresponding passages. Each of the valves (81-86) ofthe present embodiment constitutes a flow rate control valve which canregulate the degree of opening of the corresponding passage.

The air conditioning system (10) includes a circulation circuit (60) inwhich water as the heating medium circulates. The first air heatexchanger (63) and the second air heat exchanger (64) are connected inseries to the circulation circuit (60).

The first air heat exchanger (63) is provided upstream of the coolingheat exchanger (61) in the air passage (52). The first air heatexchanger (63) includes a plurality of fins (63 a), and a heat transfertube (63 b) penetrating the fins (63 a) to constitute the so-calledfin-and-tube heat exchanger. The first air heat exchanger (63) includesfin sets each containing two fins arranged in the direction of the airflow.

The first air heat exchanger (63) includes an inlet (73 a) which ispositioned in the downstream part of the air passage (52), and throughwhich water flows into the first air heat exchanger (63), and an outlet(73 b) which is positioned in the upstream part of the air passage (52),and through which water flows out of the first air heat exchanger (63).An end of a third coupling pipe (77), and an end of a fourth couplingpipe (78) are connected to the outlet (73 b) and the inlet (73 a) of thefirst air heat exchanger (63), respectively.

Like in the cooling heat exchanger (61) described above, the inlet (73a) and the outlet (73 b) of the first air heat exchanger (63) arebranched, and a plurality of paths (63 c, 63 c, . . . ) are formed as anintermediate passage between the inlet (73 a) and the outlet (73 b).

The second air heat exchanger (64) is provided downstream of theauxiliary heat exchanger (62) in the air passage (52). The second airheat exchanger (64) includes a plurality of fins (64 a), and a heattransfer tube (64 b) penetrating the fins (64 a) to constitute theso-called fin-and-tube heat exchanger. The second air heat exchanger(64) includes fin sets each containing three fins arranged in thedirection of the air flow.

The second air heat exchanger (64) includes an inlet (74 a) which ispositioned in the downstream part of the air passage (52), and throughwhich water flows into the second air heat exchanger (64), and an outlet(74 b) which is positioned in the upstream part of the air passage (52),and through which water flows out of the second air heat exchanger (64).The other end of the third coupling pipe (77) and the other end of thefourth coupling pipe (78) are connected to the inlet (74 a) and theoutlet (74 b) of the second air heat exchanger (64), respectively.

Like in the cooling heat exchanger (61) described above, the inlet (74a) and the outlet (74 b) of the second air heat exchanger (64) arebranched, and a plurality of paths (64 c, 64 c, . . . ) are formed as anintermediate passage between the inlet (74 a) and the outlet (74 b).

As described above, the first air heat exchanger (63), the thirdcoupling pipe (77), the second air heat exchanger (64), and the fourthcoupling pipe (78) are sequentially connected to constitute the closedcirculation circuit (60). The third coupling pipe (77) includes acirculating pump (65) for transferring water in the circulation circuit(60).

<Structure of Controller>

The air conditioning system (10) includes a controller (100) as acontrol section. A signal related to an operating state of the airconditioning system (10) is input to the controller (100). Based on theinput signal, the controller (100) controls cooling capacity of thechiller unit (20), an amount of water circulating in the water pump(32), the chiller pump (42), and the circulating pump (65), heatingcapacity of the electric heater (55), an amount of water sprinkled bythe sprinkler (56), the degree of opening of the motor-operated bypassvalve (44), etc. The controller (100) controls the degree of opening ofthe first to six valves (81-86) in response to switching between “heatrecovery operation” and “dehumidification-dominant operation” describedin detail later.

Working Mechanism

[Heat Recovery Operation]

Heat recovery operation is dehumidifying operation which placesimportance on energy conservation than dehumidifying capacity. The heatrecovery operation is carried out, for example, when temperature andhumidity in the room are relatively low, i.e., in winter etc. Adehumidification load in the room (e.g., a difference between targetroom humidity and current room humidity) may be detected toautomatically perform the heat recovery operation when thedehumidification load is relatively low.

In the heat recovery operation, the compressor (22), the water pump(32), the chiller pump (42), and the blower (57) of the chiller unit(20) are driven. Basically, the electric heater (55) is turned on, andthe sprinkling of the sprinkler (56) is stopped during the heat recoveryoperation. The controller (100) opens the first valve (81), the fourthvalve (84), and the sixth valve (86), and closes the second valve (82),the third valve (83), and the fifth valve (85) (see FIG. 3).

In the heat recovery operation, the refrigerant circuit (21) performs arefrigeration cycle. Specifically, the refrigerant compressed in thecompressor (22) flows through the radiator (23). In the radiator (23),the refrigerant flowing through the first heat transfer pipe (23 a)dissipates heat to water flowing through the second heat transfer pipe(23 b), and is condensed. The water heated by the second heat transferpipe (23 b) of the radiator (23) dissipates heat to the outside air inthe cooling tower (33). The refrigerant condensed in the radiator (23)is decompressed by the expansion valve (24) as a pressure reducingmechanism, and then flows through the evaporator (25). In the evaporator(25), the refrigerant flowing through the first heat transfer pipe (25a) absorbs heat from water flowing through the second heat transfer pipe(25 b), and is evaporated. The refrigerant evaporated in the evaporator(25) is sucked into the compressor (22), and is compressed.

The water cooled in the second heat transfer pipe (25 b) of theevaporator (25) passes through the chiller pump (42), and is transferredto the casing (51) of the air conditioning unit (50). In the heatrecovery operation, water passing through the inlet of the heatingmedium circuit (41) flows through the first inlet pipe (71) to enter thecooling heat exchanger (61). The water is diverted into the plurality ofpaths (61 c, 61 c, . . . ), and flows through the paths (61 c, 61 c, . .. ) to the upstream of the air flow. The water that passed through thepaths (61 c, 61 c, . . . ) of the cooling heat exchanger (61) flows intothe auxiliary heat exchanger (62) through the second coupling pipe (76).The water is diverted into the plurality of paths (62 c, 62 c, . . . ),and flows through the paths (62 c, 62 c, . . . ) to the upstream of theair flow. The water that passed through the paths (62 c, 62 c, . . . )of the auxiliary heat exchanger (62) is returned to the evaporator (25)of the heating medium circuit (41) through the second outlet pipe (74),and is cooled in the evaporator (25).

In the heat recovery operation described above, a first action ofsending the water which is cooled in the evaporator (25) of the heatingmedium circuit (41), and sequentially flowed through the cooling heatexchanger (61) and the auxiliary heat exchanger (62) to the evaporator(25) is performed.

In the circulation circuit (60), water transferred by the circulatingpump (65) flows into the second air heat exchanger (64) through thethird coupling valve (77). The water is diverted into the plurality ofpaths (64 c, 64 c, . . . ), and flows through the paths (64 c, 64 c, . .. ) to the upstream of the air flow. The water that passed through thepaths (64 c, 64 , . . . ) of the second air heat exchanger (64) is sentto the fourth coupling valve (78), and flows into the first air heatexchanger (63). The water is diverted into the plurality of paths (63 c,63 c, . . . ), and flows through the paths (63 c, 63 c, . . . ) to theupstream of the air flow. The water that passed through the paths (63 c,63 c, . . . ) of the first air heat exchanger (63) is sent to the thirdcoupling valve (77).

In the air conditioning unit (50), the outside air (OA) taken into theinlet duct (53) from the outside of the room flows through the airpassage (52) in the casing (51). The air first passes through the firstair heat exchanger (63). In the first air heat exchanger (63), the waterand the air flowing in substantially opposite directions exchange heattherebetween. Specifically, in the first air heat exchanger (63), forexample, the air of about 30° C. and the water of about 17° C. exchangeheat, thereby cooling the air of 30° C. to about 25° C. The waterflowing out of the first air heat exchanger (63) is heated to, e.g.,about 20° C.

The air cooled in the first air heat exchanger (63) passes through thecooling heat exchanger (61). In the cooling heat exchanger (61), thewater and the air flowing in substantially opposite directions exchangeheat therebetween. As a result, the air is cooled to a dew pointtemperature or lower (e.g., about 10° C.), and is dehumidified. Thewater flowing out of the cooling heat exchanger (61) is heated to, e.g.,about 15° C.

The air cooled/dehumidified in the cooling heat exchanger (61) passesthrough the auxiliary heat exchanger (62). In the auxiliary heatexchanger (62), for example, the air of about 10° C. and the water ofabout 15° C. exchange heat, thereby heating the air of about 10° C. toabout 12° C.

The air heated in the auxiliary heat exchanger (62) flows through thesecond air heat exchanger (64). In the second air heat exchanger (64),for example, the air of about 12° C. and the water of about 20° C.exchange heat, thereby heating the air to about 15° C., and cooling thewater to about 17° C.

The air heated in the second air heat exchanger (64) is further heatedby the electric heater (55). When the temperature of the air heated inthe second air heat exchanger (64) exceeds a target room temperature,the electric heater (55) may be turned off

The air dehumidified in this way is supplied to the room (5) as supplyair (SA) through the supply duct (54).

[Dehumidification-dominant Operation]

Dehumidification-dominant operation is dehumidifying operation whichplaces importance on dehumidifying capacity than energy conservation.The dehumidification-dominant operation is carried out, for example,when temperature and humidity in the room are relatively high, i.e., insummer etc. A dehumidification load in the room may be detected toautomatically perform the dehumidification-dominant operation when thedehumidification load is relatively high.

In the dehumidification-dominant operation, the compressor (22), thewater pump (32), the chiller pump (42), and the blower (57) of thechiller unit (20) are driven. Basically, the electric heater (55) isturned on, and the sprinkling of the sprinkler (56) is stopped duringthe dehumidification-dominant operation. The controller (100) opens thesecond valve (82), the third valve (83), and the fifth valve (85), andcloses the first valve (81), the fourth valve (84), and the sixth valve(86) (see FIG. 4).

In the dehumidification-dominant operation, the refrigerant circuit (21)performs the refrigeration cycle in the same manner as in the heatrecovery operation. Water cooled in the second heat transfer pipe (25 b)of the evaporator (25) passes through the chiller pump (42), and istransferred to the casing (51) of the air conditioning unit (50).

In the dehumidification-dominant operation, water passing through theinlet of the heating medium circuit (41) flows through the second inletpipe (73) to enter the auxiliary heat exchanger (62). The water isdiverted into the plurality of paths (62 c, 62 c, . . . ), and flowsthrough the paths (62 c, 62 c, . . . ) to the upstream of the air flow.The water that passed through the paths (62 c, 62 c, . . . ) of theauxiliary heat exchanger (62) flows into the cooling heat exchanger (61)through the first coupling pipe (75). The water is diverted into theplurality of paths (61 c, 61 c, . . . ), and flows through the paths (61c, 61 c, . . . ) to the upstream of the air flow. The water that passedthrough the paths (61 c, 61 c, . . . ) of the cooling heat exchanger(61) is returned to the evaporator (25) of the heating medium circuit(41) through the first outlet pipe (72), and is cooled in the evaporator(25).

In the dehumidification-dominant operation described above, a secondaction of sending the water which is cooled in the evaporator (25) ofthe heating medium circuit (41), and sequentially flowed through theauxiliary heat exchanger (62) and the cooling heat exchanger (61) to theevaporator (25) is performed.

In the air conditioning unit (50), the outside air (OA) taken into theinlet duct (53) from the outside of the room flows through the airpassage (52) in the casing (51). The air passes through the cooling heatexchanger (61), and then passes through the auxiliary heat exchanger(62). The water in the heating medium circuit (41) flows through thepaths (62 c, 62 c, . . . ) of the auxiliary heat exchanger (62), andthen flows through the paths (61 c, 61 c, . . . ) of the cooling heatexchanger (61) as described above. Thus, in the air passage (52), theair and the heating medium (water) flow substantially in the oppositedirections in the two air heat exchangers (61, 62) to exchange heattherebetween. Specifically, the two air heat exchangers (61, 62)substantially function as a single convection heat exchanger in thedehumidification-dominant operation.

Thus, when the air cooled in the first air heat exchanger (63) passesthrough the cooling heat exchanger (61) and the auxiliary heat exchanger(62), the air is cooled in both of the heat exchangers (61, 62). As aresult, the air which passed through the auxiliary heat exchanger (62)is more cooled in the dehumidification-dominant operation than in theheat recovery operation described above. This improves the dehumidifyingcapacity.

The air cooled/dehumidified in the two heat exchangers (61, 62) isheated by the second air heat exchanger (64) and the electric heater(55). The air dehumidified as described above is supplied to the room(5) as the supply air (SA) through the supply duct (54).

Advantages of First Embodiment

In the above embodiment, the air which is not cooled/dehumidified yet inthe cooling heat exchanger (61) is cooled in advance in the first airheat exchanger (63). This can reduce the cooling capacity required inthe cooling heat exchanger (61), and can reduce, for example, the amountof water flowing in the heating medium circuit (41), or the coolingcapacity required in the evaporator (25) (i.e., power of thecompressor). This can reduce energy consumption of the air conditioningsystem (10).

In the second air heat exchanger (64), heat collected from the air inthe first air heat exchanger (63) is used to heat the air. Thus, thedehumidifying capacity can be improved, and cold collected from the aircan be used to cool the air again in the first air heat exchanger (63).Further, input to the electric heater (55) can be reduced.

In the auxiliary heat exchanger (62) during the heat recovery operation,heat collected from the air in the cooling heat exchanger (61) is usedto heat the air. This can further improve the dehumidifying capacity,and can reduce the temperature of water sent to the evaporator (25) ofthe heating medium circuit (41). Thus, the cooling capacity required inthe evaporator (25) can further be reduced, and energy consumption canfurther be reduced. In addition, the input to the electric heater (55)can be reduced.

In the cooling heat exchanger (61) during the heat recovery operation,the air and the water flowing in the opposite directions exchange heattherebetween. Thus, the air flowing out of the cooling heat exchanger(61) can be cooled to a temperature close to the temperature of thewater introduced in the cooling heat exchanger (61), therebycooling/dehumidifying the air more effectively in the cooling heatexchanger (61). On the other hand, the water flowing out of the coolingheat exchanger (61) can be heated to a temperature close to thetemperature of the air flowing into the cooling heat exchanger (61).Thus, the air can be heated more effectively in the auxiliary heatexchanger (62), thereby further reducing the heating capacity requiredin the electric heater (55).

In the auxiliary heat exchanger (62) during the heat recovery operation,the air and water flowing in the opposite directions exchange heattherebetween. This can significantly heat the air, and significantlycool the water. Therefore, the cooling capacity required in theevaporator (25) can further be reduced, and the heating capacityrequired in the electric heater (55) can further be reduced.

The first air heat exchanger (63) which functions as the so-calledconvection heat exchanger can effectively cool the air. Since thetemperature of the water flowing out of the first air heat exchanger(63) is relatively high, the second air heat exchanger (64) caneffectively heat the air. Further, the second air heat exchanger (64)which also functions as the so-called convection heat exchanger caneffectively heat the air. Since the temperature of the water flowing outof the second air heat exchanger (64) is relatively low, the first airheat exchanger (63) can effectively cool the air.

In the above embodiment, the air sequentially flows through the coolingheat exchanger (61) and the auxiliary heat exchanger (62), and the watersequentially flows through the auxiliary heat exchanger (62) and thecooling heat exchanger (61) in the dehumidification-dominant operation.Thus, the air can be cooled in both of the cooling heat exchanger (61)and the auxiliary heat exchanger (62), and the operation can beperformed with priority given to the dehumidification of the air. Evenwhen the outside humidity or temperature is significantly high, latentheat of the air can reliably be handled to supply the air to the insideof the room.

In the above embodiment, the passages in the heating medium circuit (41)through which the water flows are changed in thedehumidification-dominant operation in such a manner that both of thecooling heat exchanger (61) and the auxiliary heat exchanger (62)function as the so-called convection heat exchangers. Thus, in thedehumidification-dominant operation, the two heat exchangers (61, 62)substantially function as a single convection air heat exchanger.Therefore, the air can be cooled and dehumidified more effectively.

[Alternative of First Embodiment]

The first embodiment described above may be modified in the followingmanner. In the following description, the same components as those ofthe first embodiment will not be described in detail.

<First Alternative>

An air conditioning system (10) of a first alternative shown in FIGS.5-7 includes a branch passage (66) into which part of the watercirculating in the circulation circuit (60) is diverted, and anauxiliary cooling unit (90) for cooling the water flowing through thebranch passage (66).

The auxiliary cooling unit (90) includes a refrigerant circuit (91)which is filled with a refrigerant, and performs a vapor compressionrefrigeration cycle. A compressor (92), a radiator (93), an expansionvalve (94), and an evaporator (95) are sequentially connected to therefrigerant circuit (91) of the auxiliary cooling unit (90). Therefrigerant circuit (91) is connected to the branch passage (66) throughthe evaporator (95). The evaporator (95) constitutes an auxiliarycooling section which cools the heating medium flowing through thebranch passage (66) by the refrigerant.

The branch passage (66) includes a first branch pipe (66 a) closer to aninlet of the evaporator (95), and a second branch pipe (66 b) closer toan outlet of the evaporator (95). An inlet end of the first branch pipe(66 a) is connected to an upstream end of the third coupling valve (77).A three-way valve (97) is provided at a junction between the firstbranch pipe (66 a) and the third coupling valve (77). The three-wayvalve (97) is configured to regulate the amounts of the heating mediumsent to the third coupling valve (77) and the first branch pipe (66 a)from the outlet (73 b) of the first air heat exchanger (63).Specifically, the three-way valve (97) can be switched between a statewhere the entire heating medium flowing out of the outlet (73 b) of thefirst air heat exchanger (63) is sent to the third coupling valve (77)(a state shown in FIG. 6), and a state where the heating medium flowingout of the outlet (73 b) of the first air heat exchanger (63) isdiverted to the third coupling valve (77) and the first branch pipe (66a) (a state shown in FIG. 7). The three-way valve (97) can be switchedto a state where the entire heating medium flowing out of the outlet (73b) of the first air heat exchanger (63) is sent to the first branch pipe(66 a). In this way, the three-way valve (97) constitutes a divertedflow control mechanism which regulates a flow rate of the heating mediumflowing through the branch passage (66).

In the dehumidifying operation performed by the air conditioning system(10) of the first alternative, the controller (100) controls the degreeof opening of the three-way valve (97) based on temperature and humidityof the target air, set room temperature (target temperature) and setroom humidity (target humidity).

Specifically, for example, in the normal dehumidifying operation, thecontroller (100) controls the three-way valve (97) in the state shown inFIG. 6. Thus, the entire heating medium flowing out of the outlet (73 b)of the first air heat exchanger (63) is not sent to the branch passage(66), but flows through the third coupling valve (77). Thus, in thiscase, the dehumidifying operation is performed in the same manner asdescribed in the first embodiment.

For example, when the dehumidifying operation is performed when thehumidity or temperature of the target air is excessively high, or theset room temperature or humidity is excessively low, the controller(100) controls the three-way valve (97) in the state shown in FIG. 7.Thus, part of the heating medium flowing out of the outlet (73 b) of thefirst air heat exchanger (63) is sent to the branch passage (66). Theheating medium flowing through the branch passage (66) is cooled in theevaporator (95) of the auxiliary cooling unit (90), and is then sent tothe second air heat exchanger (64). Thus, in this operation, the air canbe cooled/dehumidified also in the second air heat exchanger (64).Therefore, even when the latent heat load is high, the dehumidificationcan be performed to a preferred degree.

<Second Alternative>

In an air conditioning system (10) of a second alternative shown in FIG.8, a refrigerant circuit (130) is used as a circulation circuit in placeof the circulation circuit (60) of the first embodiment. The refrigerantcircuit (130) is configured to perform a vapor compression refrigerationcycle by circulating a refrigerant as a heating medium.

A compressor (131), a second air heat exchanger (64), an expansion valve(132), and a first air heat exchanger (63) are sequentially connected tothe refrigerant circuit (130). In the second alternative, the second airheat exchanger (64) functions as a radiator (a condenser), and the firstair heat exchanger (63) functions as an evaporator.

Specifically, when the air flowing through the air passage (52) passesthrough the first air heat exchanger (63), the refrigerant absorbs heatfrom the air to evaporate, thereby precooling the air. When the aircooled/dehumidified in the cooling heat exchanger (61) passes throughthe second air heat exchanger (64), the refrigerant dissipates heat tothe air to heat the air. In the second alternative, the heat collectedfrom the air to the refrigerant in the first air heat exchanger (63) isused to heat the air in the second air heat exchanger (64). This canreduce energy consumption of the air conditioning system (10).

<Third Alternative>

A circulation circuit (41) of a third alternative shown in FIG. 9includes a first water tank (35), a second water tank (36), and anauxiliary pump (37).

The first water tank (35) and the second water tank (36) constitute aheating medium container for temporarily containing water as a heatingmedium. The first water tank (35) is provided in the third couplingvalve (77) near an inlet end of the circulating pump (65). The auxiliarypump (37) is provided in the fourth coupling valve (78). The secondwater tank (36) is provided in the fourth coupling valve (78) near aninlet end of the auxiliary pump (37). The circulating pump (65) and theauxiliary pump (37) are centrifugal pumps, for example, and an amount ofthe heating medium transferred by each pump is variable by changing thenumber or revolutions of a motor.

The first water tank (35), the second water tank (36), the auxiliarypump (37), and the circulating pump (65) constitute a flow rate controlmechanism which separately regulates the flow rate of the water flowingthrough the first air heat exchanger (63), and the flow rate of thewater flowing through the second air heat exchanger (64).

The controller (100) of the third alternative includes a pump controlsection. The pump control section is configured to control the numbersof revolutions of motors of the circulating pump (65) and the auxiliarypump (37) (i.e., the flow rate of the heating medium).

Specifically, the pump control section regulates the flow rates of theheating medium transferred by the circulating pump (65) and theauxiliary pump (37) differently between daytime and nighttime.

In the daytime, the flow rate of water transferred by the auxiliary pump(37) is controlled to be higher than the flow rate of water transferredby the circulating pump (65) (first pump control operation).Specifically, in the first pump control operation, the flow rate ofwater flowing through the first air heat exchanger (63) is higher thanthe flow rate of water flowing through the second air heat exchanger(64). In the daytime, the temperature of the outside air (OA) is higherthan that in the nighttime. With the flow rate of the water flowingthrough the first air heat exchanger (63) controlled to be relativelyhigh, the outside air can sufficiently be cooled and dehumidified. Whenthe flow rate of the water flowing through the second air heat exchanger(64) is lower than the flow rate of the water flowing through the firstair heat exchanger (63), the amount of water which is heated in thefirst air heat exchanger (63), and is contained in the first water tank(35) increases.

In the nighttime, the flow rate of the water transferred by thecirculating pump (65) is controlled to be higher than the flow rate ofthe water transferred by the auxiliary pump (37) (second pump controloperation). Specifically, in the second pump control operation, the flowrate of the water flowing through the second air heat exchanger (64) ishigher than the flow rate of the water flowing through the first airheat exchanger (63). In the nighttime, the temperature of the outsideair (OA) is lower than that in the daytime. With the flow rate of thewater flowing through the second air heat exchanger (64) controlled tobe relatively low, excessive cooling of the outside air can be avoided.In the nighttime, a large amount of water of relatively high temperatureaccumulated in the first water tank (35) in the daytime flows throughthe second air heat exchanger (64). Thus, heat exchange between thewater and the air is accelerated in the second air heat exchanger (64),i.e., heating of the air and cooling of the water are accelerated.

When the flow rate of the water flowing through the first air heatexchanger (63) is lower than the flow rate of the water flowing throughthe second air heat exchanger (64), the amount of water which is cooledin the second air heat exchanger (64), and is contained in the secondwater tank (36) increases.

Then, when the first pump control operation is performed again in thedaytime, the flow rate of the water transferred by the auxiliary pump(37) is higher than the flow rate of the water transferred by thecirculating pump (65) as described above. Thus, a large amount of waterof relatively low temperature accumulated in the second water tank (36)in the nighttime flows through the first air heat exchanger (63).Therefore, heat exchange between the water and the air is accelerated inthe first air heat exchanger (63), i.e., cooling of the air and heatingof the water are accelerated.

In the third alternative described above, the flow rates of watertransferred by the circulating pump (65) and the auxiliary pump (37) arechanged between the daytime and nighttime, and the water is accumulatedin the water tanks (35, 36). Thus, the cold collected in the nighttimecan be used to cool the air in the daytime, and the heat collected inthe daytime can be used to heat the air in the nighttime. This canfurther reduce energy consumption of the air conditioning system (10) inthe heat recovery operation.

In the third alternative, the daytime operation and the nighttimeoperation may be switched, for example, using a timer etc., or based onthe outside temperature (for example, the first pump control operationis performed when the outside temperature detected by a sensor is higherthan a predetermined value, and the second pump control operation isperformed when the outside temperature detected by the sensor is lowerthan the predetermined value), etc.

<Fourth Alternative>

An air conditioning system (10) of a fourth alternative shown in FIG. 10includes an internal heat exchanger (28) in which water in the radiationcircuit (31) and water in the circulation circuit (60) exchange heattherebetween. Specifically, a diverting pipe (26) for diverting part ofthe water in the radiation circuit (31) is connected to the radiationcircuit (31). A flow rate control valve (27) capable of regulating itsdegree of opening is provided in the diverting pipe (26). The internalheat exchanger (28) is configured to allow heat exchange between watercirculating in the circulation circuit (60) and water diverted to thediverting pipe (26) to cool the water in the diverting pipe (26) by thewater in the circulation circuit (60).

Specifically, in the above-described dehumidifying operation, when theflow rate control valve (27) opens the diverting pipe (26) at apredetermined degree of opening, the water in the radiation circuit (31)is diverted to the diverting pipe (26). The diverted water exchangesheat with the water of relatively low temperature flowing through thecirculation circuit (60), and is cooled in the internal heat exchanger(28). Thus, in the fourth alternative, for example, when the outsidetemperature is low, cold of the water in the circulation circuit (60)can be used to cool the water in the radiation circuit (31).

<Fifth Alternative>

An air conditioning system (10) of a fifth alternative shown in FIG. 11includes an exhaust duct (59), and a duct heat exchanger (68). An end ofthe exhaust duct (59) is connected to the room (5), and the other end isopened to the outside air. Thus, the exhaust duct (59) forms an exhaustpassage through which the air in the room (5), which is target air ofthe air conditioning system (10), is discharged outside as exhaust air(EA). The duct heat exchanger (68) is arranged inside of the exhaustduct (59) to occupy the whole cross sectional area of the exhaust duct(59). The duct heat exchanger (68) is connected to a pipe between thefirst air heat exchanger (63) and the second air heat exchanger (64)(the third coupling valve (77)). Specifically, the duct heat exchanger(68) constitutes a sensible heat exchanger in which the water sent fromthe first air heat exchanger (63) to the second air heat exchanger (64)and the air sent from the room (5) to the outside exchange heat.

According to the fifth alternative, for example, in summer, cold of theroom air can be added to the water in the circulation circuit (60).Thus, in the air conditioning unit (50), the cold collected to thecirculation circuit (60) can be used to cool the air in the first airheat exchanger (63). For example, in winter, heat of the room air can beadded to the water in the circulation circuit (60). Thus, in the airconditioning unit (50), the heat collected to the circulation circuit(60) can be used to heat the air in the second air heat exchanger (64).

<Sixth Alternative>

An air conditioning unit (50) of an air conditioning system (10) of asixth alternative shown in FIG. 12 is configured to send supply air (SA)to three rooms (a first room (5 a), a second room (5 b), and a thirdroom (5 c)). Specifically, an outlet end of the supply duct (54) of theair conditioning unit (50) is branched into three air supply parts (afirst air supply part (54 a), a second air supply part (54 b), and athird air supply part (54 c)). An outlet end of the first air supplypart (54 a) is opened in the first room (5 a), an outlet end of thesecond air supply part (54 b) is opened in the second room (5 b), and anoutlet end of the third air supply part (54 c) is opened in the thirdroom (5 c). An exhaust duct (59 a) is connected to the first room (5 a).

The air conditioning system (10) of the sixth alternative includes firstand second auxiliary air conditioning units (120, 130). The firstauxiliary air conditioning unit (120) is concerned with the second room(5 b), and the second auxiliary air conditioning unit (130) is concernedwith the third room (5 c).

Each of the auxiliary air conditioning units (120, 130) includes acasing (121, 131) which forms an air passage (122, 132), an inlet duct(123, 133) which connects an inlet end of the air passage (122, 132) anda room (5 b, 5 c), and a supply duct (124, 134) which connects an outletend of the air passage (122, 132) and the room (5 b, 5 c).

In the air passage (122, 132) of each of the auxiliary air conditioningunits (122, 132), an air heat exchanger (125, 135), an electric heater(126, 136), a sprinkler (127, 137), and a blower (128, 138) aresequentially arranged in a direction from upstream to downstream of theair passage. Heat transfer pipes of the air heat exchangers (125, 135)are filled with a heating medium such as water etc.

In the air conditioning system (10), the air conditioning unit (50) isoperated in association with each of the auxiliary air conditioningunits (122, 132). The air cooled/dehumidified in the air conditioningunit (50) is divided into the three air supply parts (54 a, 54 b, 54 c)from the supply duct (54), and is supplied to the rooms (54 a, 54 b, 54c).

In each of the auxiliary air conditioning units (120, 130), the room air(RA) in each of the room (5 b, 5 c) is introduced into the air passage(122, 132) through the inlet duct (123, 133). The air iscooled/dehumidified by the heating medium flowing through the air heatexchanger (125, 135), and is then heated by the electric heater (126,136). The air dehumidified in this manner is supplied to the rooms (5 b,5 c) as supply air (SA).

<Seventh Alternative>

An air conditioning system (10) of a seventh alternative shown in FIG.13 includes a branch duct (140), and an air flow control valve (141). Aninlet end of the branch duct (140) is connected to the inlet duct (53).An outlet end of the branch duct (140) is opened between the second airheat exchanger (64) and the electric heater (55) in the air passage(52). Specifically, the branch duct (140) constitutes a bypass passagewhich transfers the air in the air passage (52) upstream of the firstair heat exchanger (63) to the downstream of the second air heatexchanger (64). The air flow control valve (141) constitutes a bypassflow control mechanism which regulates the flow rate of the air flowingthrough the branch duct (140). The bypass flow control mechanism may beother mechanisms, such as a damper etc.

In the seventh alternative, the controller (100) controls the air flowcontrol valve (141) based on operating conditions, thereby allowingoperation suitable for a target latent or sensible heat load.

Specifically, for example, when the target latent heat load is high, thedegree of opening of the air flow control valve (141) is reduced toreduce the flow rate of the air flowing through the branch duct (140).Thus, the flow rate of the air passing through the first air heatexchanger (63) and the cooling heat exchanger (61) is relatively high,and the air can be cooled/dehumidified to sufficiently handle the latentheat load.

For example, when the target latent heat load is not very high, but thetarget sensible heat load is relatively high, the degree of opening ofthe air flow control valve (141) is increased to increase the flow rateof the air flowing through the branch duct (140). Thus, the flow rate ofthe air passing through the first air heat exchanger (63) and thecooling heat exchanger (61) is relatively low. This reduces a coolingload of the evaporator (25) of the heating medium circuit (41), therebyreducing cooling capacity required in the evaporator (25).

In the seventh alternative described above, the operation can beperformed based on the latent or sensible heat load. Thus, the latentand sensible heat loads can reliably be handled while keeping the energyconsumption low. The latent heat load to be handled by the airconditioning system (10) can be calculated, for example, from adifference between a target room humidity set in the controller (100),and humidity of the outside air detected by a sensor etc. The sensibleheat load to be handled by the air conditioning system (10) can becalculated, for example, from a difference between a target roomtemperature set in the controller (100), and temperature of the outsideair detected by a sensor etc.

In the seventh alternative, the air flow control valve (141) is fullyopened in winter etc., i.e., in heating operation for heating theoutside air by the electric heater (55), or heating/humidifyingoperation for heating the outside air by the electric heater (55), andhumidifying the heated air by the sprinkler (56). Specifically, thefirst air heat exchanger (63), the cooling heat exchanger (61), theauxiliary heat exchanger (62), and the second air heat exchanger (64)are stopped in the heating operation or the heating/humidifyingoperation. At this time, the flow rate of the air passing through thebranch duct (140) is the highest. Thus, the flow rate of the air passingthrough each of the heat exchangers (61-64) can be reduced as much aspossible, and pressure loss in each of the heat exchangers (61-64) canbe reduced as much as possible. This can reduce power required by theblower (57) in the heating operation and the heating/humidifyingoperation.

The outlet end of the branch duct (140) of the seventh alternative maybe opened in the other part. Specifically, for example, the outlet endof the branch duct (140) may be opened downstream of the electric heater(55) as shown in FIG. 14.

[Other Embodiments]

The above embodiment may be modified in the following manner.

The air conditioning system (10) according to the above embodiment (andthe alternatives) takes the outside air (OA) into the air passage (52)to cool and dehumidify the air. However, the air conditioning system maytake the room air (RA) into the air passage (52) to cool and dehumidifythe room air.

In the above embodiment, the electric heater (55) is used as the heatingsection provided in the air passage (52) to heat the air. However, theheating section may be a condenser of a refrigerant circuit whichperforms a refrigeration cycle, or other heating members.

Two or more of the first to seventh alternatives may be combined toconstitute the air conditioning system (10). The above-describedembodiment has been set forth merely for the purposes of preferredexamples in nature, and are not intended to limit the scope,applications, and use of the invention.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for dehumidificationsystems which cool and dehumidify air, and supply the dehumidified airto the inside of the room.

DESCRIPTION OF REFERENCE CHARACTERS

10 Air conditioning system (dehumidification system)

25 Evaporator (cooling section)

35 First water tank (flow rate control mechanism)

36 Second water tank (flow rate control mechanism)

37 Auxiliary pump (flow rate control mechanism)

41 Heating medium circuit

51 Casing

52 Air passage

55 Electric heater (heating section)

59 Exhaust passage (exhaust duct)

61 Cooling heat exchanger

61 c Paths (intermediate passage)

62 Auxiliary heat exchanger

62 c Paths (intermediate passage)

63 First air heat exchanger

63 c Paths (intermediate passage)

64 Second air heat exchanger

64 c Paths (intermediate passage)

65 Circulating pump (flow rate control mechanism)

66 Branch passage

68 Duct heat exchanger (latent heat exchanger)

71 a Inlet

71 b Outlet

72 a Inlet

72 b Outlet

73 a Inlet

73 b Outlet

74 a Inlet

74 b Outlet

95 Evaporator (auxiliary cooling section)

97 Three-way valve (diverted flow control mechanism)

130 Circulation circuit (refrigerant circuit)

140 Branch duct (bypass pipe)

141 Air flow control valve (bypass flow control mechanism)

1. A dehumidification system comprising: a casing which forms an airpassage through which air flows; a heating medium circuit which includesa cooling section for cooling a predetermined heating medium, and inwhich the heating medium circulates; a cooling heat exchanger which isconnected to the heating medium circuit, and is provided in the airpassage to cool and dehumidify the air by the heating medium flowingthrough the cooling heat exchanger to supply the dehumidified air to theinside of a room; an auxiliary heat exchanger which is connected to theheating medium circuit in series with the cooling heat exchanger, and isarranged downstream of the cooling heat exchanger in the air passage; afirst air heat exchanger which is connected to a circulation circuit inwhich the predetermined heating medium circulates, and is arrangedupstream of the cooling heat exchanger in the air passage; and a secondair heat exchanger which is connected to the circulation circuit inseries with the first air heat exchanger, and is arranged downstream ofthe auxiliary heat exchanger in the air passage, wherein the heatingmedium circuit performs a first action of sending the heating mediumwhich is cooled in the cooling section, and sequentially flowed throughthe cooling heat exchanger and the auxiliary heat exchanger to thecooling section.
 2. The dehumidification system of claim 1, furthercomprising: a heating section which is arranged downstream of the secondair heat exchanger in the air passage to heat the air.
 3. Thedehumidification system of claim 1, wherein the cooling heat exchangerincludes an inlet which is positioned in a downstream part of the airpassage, and through which the heating medium flows into the coolingheat exchanger, an outlet which is positioned in an upstream part of theair passage, and through which the heating medium flows out of thecooling heat exchanger, and an intermediate passage formed between theinlet and the outlet.
 4. The dehumidification system of claim 3, whereinthe auxiliary heat exchanger includes an inlet which is positioned inthe downstream part of the air passage, and through which the heatingmedium flows into the auxiliary heat exchanger, an outlet which ispositioned in the upstream part of the air passage, and through whichthe heating medium flows out of the auxiliary heat exchanger, and anintermediate passage formed between the inlet and the outlet.
 5. Thedehumidification system of claim 4, wherein the first air heat exchangerincludes an inlet which is positioned in the downstream part of the airpassage, and through which the heating medium flows into the first airheat exchanger, an outlet which is positioned in the upstream part ofthe air passage, and through which the heating medium flows out of thefirst air heat exchanger, and an intermediate passage formed between theinlet and the outlet.
 6. The dehumidification system of claim 5, whereinthe second air heat exchanger includes an inlet which is positioned inthe downstream part of the air passage, and through which the heatingmedium flows into the second air heat exchanger, an outlet which ispositioned in the upstream part of the air passage, and through whichthe heating medium flows out of the second air heat exchanger, and anintermediate passage formed between the inlet and the outlet.
 7. Thedehumidification system of claim 1, wherein the heating medium circuitis configured to perform the first action, and a second action ofsending the heating medium which is cooled in the cooling section, andsequentially flowed through the auxiliary heat exchanger and the coolingheat exchanger to the cooling section in a switchable manner.
 8. Thedehumidification system of claim 1, further comprising: a branch passagewhich diverts the heating medium circulating in the circulation circuit,and introduces the diverted heating medium into the circulation circuit;an auxiliary cooling section which cools the heating medium flowingthrough the branch passage; and a diverted flow control mechanism whichregulates a flow rate of the heating medium flowing through the branchpassage.
 9. The dehumidification system of claim 1, further comprising:a flow rate control mechanism which separately regulates a flow rate ofthe heating medium flowing through the first air heat exchanger, and aflow rate of the heating medium flowing through the second air heatexchanger.
 10. The dehumidification system of claim 1, furthercomprising: an exhaust passage through which the air in the room isdischarged outside; and a sensible heat exchanger in which the heatingmedium flowing through the circulation circuit and the air flowingthrough the exhaust passage exchange heat.
 11. The dehumidificationsystem of claim 1, further comprising: a bypass passage which transfersthe air in the air passage upstream of the first air heat exchanger tothe downstream of the cooling heat exchanger; and a bypass flow controlmechanism which regulates a flow rate of the air flowing through thebypass passage.